A need exists to be able to tailor cosmetic products into numerous versions, so as to be able to accommodate various situations.
Manufacturers have invested a great deal in order to be able to cope with the diversity of cases, by producing the largest number of possible versions. Although they offer numerous variants, it often happens that this solution is not satisfactory.
For example, taking the case of a person treating their skin, the latter can:                either apply one and the same product throughout the duration of a treatment,        or apply several products corresponding to the prescription required by their skin in the course of the treatment.        
The first approach, though it does not give optimum results, presents the advantage of being simple.
The second approach may give better results but is complex and expensive. Moreover, the person must find the instructions corresponding to their case, and know how to translate them into a mode of application. This approach also presents the drawback of requiring high concentration from the user so as not to confuse the various products used during treatment.
Hitherto there does not exist any system making it possible to optimize a cosmetic treatment, in a simple manner. For this reason, in general, users must content themselves with the first approach and employ just a single product. This may give rise to mistakes of overdosage or under-dosage.
The same holds in respect of protection from the sun. Indeed, it is known that the dosage of photoprotection active agents may evolve over time as the skin tans and becomes protected by tanning. A significant dosage is required during the first few days of exposure. Conversely, the dosage may be reduced after a few days. It is difficult to optimize the strength of the photoprotection product. It follows that users sometimes try to optimize the application of the product themselves. For this purpose, people generally use their sunscreen protection product at the start of holidays and then abandon it after a few days. This “intuitive” optimization approach often gives undesirable results.
The same holds in respect of care products for the scalp, where some users are seen to sometimes hesitate between continuing a treatment and stopping it.
Moreover, a difficulty related to certain treatments resides in the fact that these treatments do not give visible effects during application or immediately after application. Thus, the user cannot be guided by the immediate results in order to decide whether or not to continue the treatment, and still less whether the use should modify the dosage. The user sometimes follows a general prescription which is not necessarily tailored to their case. The treatments concerned are for example treatments for strengthening the nails, the armpits against perspiration, the lips and the skin to combat dryness, hair which is too greasy or too dry.
It is also possible to cite treatments affording a durable colour, for example for dyeing the hair or skin. In these cases, the user, seeing the result, is more comfortable with optimizing the use of the products during subsequent applications. However, in so far as it is difficult to evaluate the evolution of the colour over time, it is also difficult to identify the best application procedures for maintaining it over time.
Finally, the user is often faced with a problem of choice when confronted with several versions. They may hesitate to choose one strength rather than another. They may purchase several versions but this solution is not practical, if only in regard to the clutter and cost imposed by this solution.
Moreover, although manufacturers try to clearly identify the potency level of their products, and display corresponding information on the packaging, the user may make a mistake at the time of application. The business of identifying the brands requires the use of colours or logos on the packaging, serving as recognition signs for consumers. If the manufacturers add other signs so that the users can recognize the potency level, these additional signs may be difficult to recognize or to memorize.
The requirement to provide for various strength levels relates for example to products for protection against the sun, drying, heat or cold, antiperspirant and deodorant products, fragrances and hair gels.
The products can be made with several strength levels or made with a single potency level and rely on the user to dose the application of the product so as to adjust its strength.
For example, antiperspirants can be produced in several versions. However, most of the time, manufacturers do not opt for this approach since studies show that users do not wish to burden themselves with the clutter of several products. The user can adjust the potency of their product by altering the amount applied. However, this poses problems since it is difficult to apply small amounts. It is fairly easy to apply large amounts but the user may then be bothered by the problems of discomfort that this generates, for example as regards the moist feel and look persisting for a number of minutes after application.
Moreover, certain products may not be the subject of versions in several potency levels. This is typically the case for products which already exist in multi-coloured form, such as hair dyeing products for example.
Producing versions of these dyeing products in different potency levels would unacceptably multiply the number of products to be offered. In these cases, the user has no solution for adapting their product as a function of the time of use, and is often far removed from an optimized result.
Patent application FR 2 807 346 describes a flask comprising an electronic circuit making it possible to deliver a message when the user presses a product delivery button. The flask may comprise at least one sensor of an exterior physical parameter, in particular a sensor of ambient luminosity and/or of ambient temperature. The electronic circuit may comprise a microcontroller receiving data from a clock. The message delivered may take account of the time or the period elapsed since the last use.
Patent application WO 98/30189 describes a packaging device making it possible to modify a cosmetic composition as a function of a physical quantity of the ambient environment, measured by a sensor.